Various machines of the hybrid type are already known in the prior art. For example, U.S. Pat. No. 4,306,164 presents a motor of the stepping homopolar type, that is to say having a unidirectional magnet flux in only one direction. In this diphase motor the polarisation magnet is placed at the centre of the structure, on the movable assembly or the fixed assembly. The two faces of the motor are implemented by two coils, the winding axis of which corresponds to the rotation axis (winding said to be “global”) and each coil is extended, on either side, by toothed rings connected by a magnetic flux return. The phase difference between the teeth of the various phases at the stator and rotor allow viability of the diphase functioning. Through the fact that the magnet is situated at the centre of the structure, the two phases of the motor are completely dependent and cannot function without the presence of the other. In addition, the homopolar character of the motor (the magnetic field passing through the coils is always oriented in a single direction) has the consequence of limiting the torque that can be achieved since the magnetic flux generated by the magnet always circulates in the single direction around each coil so that the variation in flux as a function of the rotation is intrinsically limited. The circulation of the flux of this type of motor is transverse.
Moreover, hybrid machines are already known having two magnets with opposite polarities disposed at the rotor as for example in U.S. Pat. No. 4,339,679. This type of motor solves the previously mentioned problem by making it possible to reverse the magnetic flux generated by the magnets through each of the phases, intrinsically increasing the torque factor of the motor or generator. To do this, the motor comprises, at the rotor, two superimposed modules consisting of magnets extended on either side by toothed ferromagnetic rings, and has a stator having a plurality of toothed ferromagnetic poles around which coils are wound. The coils being installed on an axis transverse to the rotation axis, the magnetic flux circulates from pole to pole on a path that is no longer exclusively transverse. This topology has several drawbacks.
First of all, the winding of each pole (so-called “concentrated” winding) gives rise to an increased difficulty in implementation. Each coil must be installed around each pole. To benefit from all the action of the periphery of the motor there are therefore necessarily a plurality of coils belonging to each phase, increasing the number of manipulations. In addition, to keep an optimum space factor and shape factor (in order to reduce the intrinsic resistance of each coil), each pole must be formed, that is to say have a pole head, further complicating the implementation and thus promoting the magnetic saturation of the poles, which therefore prevents the motor from keeping advantageous characteristics at high currents.
This type of motor also has another significant drawback. This is because, even if this topology makes it possible to respond to the reversal of the direction of the magnetic field passing through each coil, having a plurality of phases distributed over the periphery of the motor necessarily means that each phase does not benefit from all the rotor teeth (half the rotor teeth are active for a given phase at a given position). Thus, to keep the benefits of the hybrid motor, these motors are therefore particularly advantageous when used with many relatively large teeth, around 50 teeth per toothed ring at the rotor typically. This high number of teeth, though it is advantageous for generating a more generous torque, is nevertheless to the detriment of tooth to tooth magnetic leakages, which are greater than in a machine such as U.S. Pat. No. 4,306,164. It should also be added that the coupling between the phases is not zero, giving rise to an unfavourable mutual inductance.